pdfminer.pdfparser.PDFSyntaxError: Invalid object number: objid=743

pdf2txt crashes when using it on a password protected PDF:
Traceback (most recent call last):
  File "/usr/bin/pdf2txt", line 101, in <module>
    if __name__ == '__main__': sys.exit(main(sys.argv))
  File "/usr/bin/pdf2txt", line 95, in main
    caching=caching, check_extractable=True)
  File "/usr/lib/python2.7/dist-packages/pdfminer/pdfinterp.py", line 820, in process_pdf
    doc.set_parser(parser)
  File "/usr/lib/python2.7/dist-packages/pdfminer/pdfparser.py", line 327, in set_parser
    self.info.append(dict_value(trailer['Info']))
  File "/usr/lib/python2.7/dist-packages/pdfminer/pdftypes.py", line 132, in dict_value
    x = resolve1(x)
  File "/usr/lib/python2.7/dist-packages/pdfminer/pdftypes.py", line 60, in resolve1
    x = x.resolve()
  File "/usr/lib/python2.7/dist-packages/pdfminer/pdftypes.py", line 49, in resolve
    return self.doc.getobj(self.objid)
  File "/usr/lib/python2.7/dist-packages/pdfminer/pdfparser.py", line 457, in getobj
    raise PDFSyntaxError('Invalid object number: objid=%r' % (objid))
pdfminer.pdfparser.PDFSyntaxError: Invalid object number: objid=743

The error is not very user-friendly.

ProblemType: Bug
DistroRelease: Ubuntu 12.10
Package: python-pdfminer 20110515+dfsg-1
ProcVersionSignature: Ubuntu 3.5.0-22.34-generic 3.5.7.2
Uname: Linux 3.5.0-22-generic i686
ApportVersion: 2.6.1-0ubuntu10
Architecture: i386
Date: Wed Jan 30 20:08:56 2013
MarkForUpload: True
PackageArchitecture: all
SourcePackage: pdfminer
UpgradeStatus: Upgraded to quantal on 2012-10-25 (97 days ago)